Update HomographWs when chaning defaultVernWs Ethnologue code

LT-13893 Crashes due to not updating HomographWs on Ethnologue code change

This would also apply to other crashes caused by changes in to the
DefaultVernacularWritingSystem.Id
that can occur such as making changes to script name, variant name and
region name.

Change-Id: I43b8bd33d1d6b76e7f71ff2e597827a04df66480